Jake has a bag that contains 5 blue marbles, 7 green marbles, and 3 red marbles. Jake selects a blue marble and does not place it back in the bag. What is the probability that his next marble will be a green marble?

The answer is Definitely 3 over 14

associative property of multiplication

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.